Tribological properties of nickel-copper multilayer film on beryllium bronze substrate

Abstract

In this paper, the electrodeposition of Cu/Ni multilayer coatings with sublayer thickness of 8–300 nm from single bath on beryllium bronze substrate has been carried out. The electrodeposited coatings consisted of alternate layers of nickel and pure copper with different layers of thickness. Friction and wear measurements have been conducted on Cu/Ni multilayer coatings. The structure and crystal grain size of the multilayers were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the deposited multilayer was highly dense and free from porosity. The grain size of the multilayers became small with decreasing layer of thickness. Wear test showed that the anti-wear properties of the multilayers were influenced by the ratio of layer thickness of nickel and copper and by the thickness of single-layer spacing. The most wear-resistant coating was the Cu/Ni multilayer which had the smallest nickel layer thickness (8 nm) with a 2:1 layer thickness of copper and nickel. Both multilayer coatings showed less wear than coatings of pure copper and nickel deposited from the same solution. The increase in the wear resistance of the multilayers was attributed to the layer microstructure and grain size strengthening. It was also found that there was no obvious change in the friction coefficient of the multilayers with different layers of thickness.